In a wireless telecommunications system, services for broadcast or multicast of messages and data to user equipment (UE) can be provided. Such services, referred to as multimedia broadcast multicast services (MBMS), can be transmitted throughout a single cell or throughout several contiguous or overlapping cells of the system, with a set of cells receiving an MBMS referred to as a service area.
Typically, transmission for an MBMS occurs over two channels: a multicast control channel (MCCH) and a multicast traffic channel (MTCH). The MTCH delivers content of the MBMS, and the MCCH delivers control information related to the MBMS. The MCCH might include key control information that specifies how the content in the MTCH is to be delivered for example, and MCCH channels are used as point-to-multipoint downlink channels to transmit MCCH information. In general, one cell has one corresponding MCCH.
In the Long Term Evolution (LTE) architecture, an enhanced version of MBMS (eMBMS), referred to as Multicast-Broadcast Single-Frequency Network (MBSFN), supports broadcast only services. A plurality of MBSFN areas can be defined, each having an MCCH channel to transmit MCCH information to all UEs in the MBSFN area in question.
MBMS information on the MCCH channel is transmitted according to a fixed schedule, which is common for all services. Thus, the majority of MCCH information is transmitted periodically based on a repetition period. This MCCH information is repeated a configurable number of times with exactly the same content. The time period in which the content of this MCCH information remains unchanged is called the ‘modification period’.